GM-GMC: fuel filter gm products, gm products, gmc van

Question
Thank you for taking my question.
I have replaced tens of fuel filters on various cars and light trucks over the years but I have trouble with the GM products. I am used to the typical style with 3/8" fuel line which fastens to the filter with a flared line with an o ring and tubing nut and recently on a 2001 Blazer with the plastic clips on one side and tubing nut on the other. They seem to be very difficult to separate on the steel tubing side. I opened the fuel tank vent, the release the pressure at the schrader valve and released the plastic tubing from the filter. I had to cut the tubing next to the filter on the steel line and put in a repair kit which is commonly sold which has the flared end and fitting and a 3/8 brass union with compression fittings on the other. The problem is that there never seems to be enough room to get a straight portion of the fuel line where its convenient to work.
I got the job done fine but this also happened to me on my older GMC van and I wondering if I am doing something wrong or if you have any trick to undo the fittings.
If this happens commonly, I am wondering why GM didn't change the design many years ago?
I would appreciate any advice for what should be a simple maintenance procedure.

Answer
Joe,  

  Well your definetly right, I have had some tough ones with the Gm filters as well. Basicaly I find that I spray the two line ends with some penetrating oil before I get started then usually go on to something else and come back to the filter, this has helped in alot of cases. I also find that havin a 20mm wrench really helps grab the filter end properly and although not included in most wrench sets its a good addition. If I get a really tight one or one that the line nut is already rounded off or on its way to being rounded off, I like to use a pair of flat Vise-Grips usually the clamping force added to the twisting is enough to break most loose. I have run into the plastic clips being hard and full of dirt and so far have not figured out a failsafe way to get these undone, especially the connections on top of fuel tanks! Hope this helps!